HVAC Practive midterm 56

Question 1 of 56

Medal-premium 1

On a standing pilot gas furnace the thermocouple must be replaced when?

Select one of the following:

  • its not positioned properly

  • The millivolt reading is 28 or above

  • the millivolt reading is 22 or below

  • the tip of the thermocouple is in the tip if the pilot flame is 3/8

Question 2 of 56

Medal-premium 1

natural gas pressure at the main line is recorded at 7" WC (water column), But at the gas manifold it reads 1.5 WC. What is most likely to be the cause of this?

Select one of the following:

  • A defective main line regulator

  • Too large of a gas valve

  • plugged burner orifices

  • A defective pressure regulator on the gas valve

Question 3 of 56

Medal-premium 1

A technician servicing a gas fired furnace notices that only four out of five ribbon burners are firing simultaneously . What could be the problem with the system?

Select one of the following:

  • Too much gas pressure

  • Too little gas pressure

  • Burners not aligned correctly

  • A defective gas valve

Question 4 of 56

Medal-premium 1

Technician A says if a combination gas valve needs to be replaced if there are 24 volts present to the gas valve and it will not open.

Technician B says that if a combination gas valve has a new thermocouple and the pilot will not stay lit the gas valve needs to be replaced.

Which technician is correct?

Select one of the following:

  • Tech A

  • TECH B

  • Both are right

  • Both are wrong

Question 5 of 56

Medal-premium 1

What should be the first step that a technician should take if the gas pressure at the manifold is too high?

Select one of the following:

  • adjust the pressure regulator clockwise

  • adjust the pressure regulator counter clockwise

  • replace the pressure regulator

  • replace the combination gas valve

Question 6 of 56

Medal-premium 1

If the glame is lifting off the burner port what should the technician do to correct this problem?

Select one of the following:

  • Adjust the primary air by closing the air shutter

  • adjust the primary air by opening the air shutter

  • replace the burner

  • decrease the min gas pressure.

Question 7 of 56

Medal-premium 1

a step down transformer is reading 0 ohms at its secondary winding. what is the possible cause of this problem?

Select one of the following:

  • An open primary winding

  • an open secondary winding

  • A shorted primary winding

  • A shorter secondary winding

Question 8 of 56

Medal-premium 1

when a fan centre relay needs to be tested for 124 volts, what two terminals are used when measuring for transformer output voltages?

Select one of the following:

  • Terminals "R" and "W"

  • Terminals "R" and "G"

  • Terminals "R" and "Y"

  • Terminals "R and "C'

Question 9 of 56

Medal-premium 1

On a call for heat what two terminals should be closed on the thermostat?

Select one of the following:

  • Terminals "R" and "W"

  • Terminals "R" and "G"

  • Terminals "R" and "Y"

  • Terminals "R" and "C"

Question 10 of 56

Medal-premium 1

when a thermostat sub base fan selector switch is moved to the fan "ON" postition, what two terminals will close in the thermostat.

Select one of the following:

  • Terminals "R" and "W"

  • Terminals "R" and "G"

  • Terminals "R" and "Y"

  • Terminals "R" and "C"

Question 11 of 56

Medal-premium 1

A new thermostat was recently replaced. The technician observes that the burner cycle is not long enough. the most likely cause would be?

Select one of the following:

  • A defective thermostat

  • Low gas pressure

  • the anticipator needs adjusting

  • A defective gas valve

Question 12 of 56

Medal-premium 1

A customer has replaced a mercury bulb thermostat but complains that the burners will not shut off and the house is getting too hot. The cause would be?

Select one of the following:

  • A defective limit control

  • A defective gas valve

  • The thermostat is not properly level

  • the anticipator is set too low

Question 13 of 56

Medal-premium 1

A bimetal fan control will not turn the indoor blower off. As a result cool air passes through the registers between furnace cycles. What is the possible cause of the problem.

Select one of the following:

  • The heating circuit is open on limit.

  • the fan control contacts are stuck open

  • the fan control contacts are stuck closed

  • there is a defective gas valve

Question 14 of 56

Medal-premium 1

residents are complaining of experiencing sumptoms of headaches, watery eyes and nausea.

Tech A says the heat exchanger is cracked

Tech B says the furnace may only need cleaning and the heat exchanger is possibly plugged.

Whos correct?

Select one of the following:

  • Tech A

  • Tech B

  • Both are correct

  • Both are incorrect

Question 15 of 56

Medal-premium 1

A belt driver motor has recently been replaced but the furnace is shutting off on limit control. the most likely cause is that .

Select one of the following:

  • A. the motor is running in the wrong direction

  • the motor is defective

  • the motor is too large

  • the motor mount is not correct.

Question 16 of 56

Medal-premium 1

upon testing a motor winding for continuity the technician records 3 ohms. The winding resistance should be 8 Ohms. The technician concludes that:

Select one of the following:

  • The winding is open

  • The winding is shorted

  • the winding is grounded

  • the motor is within the satisfactory operating conditions

Question 17 of 56

Medal-premium 1

A run capacitor is tested with an analog meter. The needle moves towards zero then back to infinity. What is the condition of the capacitor?

Select one of the following:

  • The capacitor is open.

  • The capacitor is good

  • The capacitor should not be used

  • The capacitor needs to be of a higher mfd rating

Question 18 of 56

Medal-premium 1

The temperature rise of a particular furnace states that it should be between 35F and 65F. The furnace is operating at 20F temperature rise with the proper gas pressure at the manifold. What could be done to solve this problem.

Select one of the following:

  • Add more outside air to the basement

  • increase the indoor blower motor speed

  • Decrease the indoor motor blower speed

  • replace the air filter with a more efficient type.

Question 19 of 56

Medal-premium 1

A belt driven motor has been replaces, but quickly gets hot and stops just short of burning out. Which of the following could cause the problem:

Select one of the following:

  • A fan belt that is too tightly adjusted

  • A fan belt that has only 1" of slack between the pulleys

  • The pulley on the motor is too small

  • none of the above.

Question 20 of 56

Medal-premium 1

A combination fan/limit control has been replaced. The indoor blower motor runs too long and the residents complain of cooler airflow. The technician should:

Select one of the following:

  • Replace the control again

  • Adjust the limit setting

  • Lengthen the fan off setting.

  • Check the readjust the fan-off differential

Question 21 of 56

Medal-premium 1

A service call is made to a customer who complains that when his furnace ignites, the flame rolls out in front of the head exchanger.

Technician A says that it is due to poor draft possibly a blocked flue or heat exchanger

Technician B says that it has to do with the limit control or the fan switch control circuit.

Select one of the following:

  • Technician A

  • Technician B

  • Both Technician are correct

  • Both Technicians are incorrect

Question 22 of 56

Medal-premium 1

A customer complains of headaches, sleepiness and nausea.

Technician A finds a crack in the head exchanger and says that the furnace should be shut down.

Technician B says that the crack isnt too serious and the furnace can operate temporarily but it must be cleaned.

Select one of the following:

  • Tech A is correct

  • Tech B is correct

  • Both technicians are correct

  • Both technicans are incorrect

Question 23 of 56

Medal-premium 1

A technician is servicing a standing pilot gas-fired furnace. The complaint is that the burners are not lighting. where should the technician start trouble shooting the system?

Select one of the following:

  • At the transformer secondary and at the combination gas valve

  • At the transformer primary only.

  • At the primary limit control

  • at the fan limit controls.

Question 24 of 56

Medal-premium 1

On a spark ignition system, The spark for the ignition continues with no ignition of gas at the burners.

Technician A Concludes that the thermostat is defective.

Technician B Concludes that it is possibly the control module

Which is correct?

Select one of the following:

  • Technician A

  • Technician B

  • Both are correct

  • Both technicians are incorrect

Question 25 of 56

Medal-premium 1

Which of the following is the correct test for a faulty cable on a direct spark ignition system?

Select one of the following:

  • A voltage check

  • A continuity check

  • An amerpage check

  • none of the above

Question 26 of 56

Medal-premium 1

A customer complains that the burners light on her system, But then immediately shut down. The problem is most likely to be?

Select one of the following:

  • In the control module

  • in the control transformer

  • in the limit control

  • in the gas valve

Question 27 of 56

Medal-premium 1

Which of the following would not be a proper procedure to perform on a direct spark ignition system where the spark continues, the burners light and the flames are immediately extinguished?

Select one of the following:

  • Check that the sensor is positioned in the flame correctly

  • check for the proper flame rectification

  • check for a proper grounding terminal

  • check that there is proper gas flow to the pilot

Question 28 of 56

Medal-premium 1

A hot surface ignition system does not ignite the main burner. after measuring voltage to the igniter the technician should:

Select one of the following:

  • Perform a resistance test on the igniter

  • Replace the flame sensor

  • Replace the main gas valve

  • Replace the control module

Question 29 of 56

Medal-premium 1

The burners of a gas furnace that is equipped with a 115-Volt hot surface igniter lights for approximately 7's and then goes out. what is the problem that could cause this symptom.

Select one of the following:

  • A faulty igniter

  • A faulty transformer secondary winding

  • burner shutting off on high limit control

  • a faulty sensor

Question 30 of 56

Medal-premium 1

The burners on a furnace having a hot surface ignition system light up but quickly shut off.

Technician A states that after testing the gas valve he determined that it has shorter

Technician B Visually checked the flame sensor, cleaned it and performed a continuity test. he faults a dirty sensor.

Whos correct?

Select one of the following:

  • Technician A

  • Technician B

  • Both Technicians are correct

  • Both technicians are incorrect

Question 31 of 56

Medal-premium 1

The thermostat on a mid efficiency gas furnace with a hot surface ignition system is placed on a call for heat. The burners do not light, but the igniter does glow. Which of the following would be the next step to take when troubleshooting the system?

Select one of the following:

  • test the flame sensor

  • test the gas valve and the gas manifold pressure

  • test the primary limit control and the fan control

  • test the thermostat

Question 32 of 56

Medal-premium 1

The draft pressure switch on a mid effciency gas furnace with a hot surface ignition system is placed on a call for heat. the burners do not light, but the igniter does glow. Which of the following would be the next step to take when troubleshooting the system?

Select one of the following:

  • Test the flame sensor

  • test the gas valve and the gas manifold pressure.

  • a defective inducer draft motor

  • a defective flame roll out sensor

Question 33 of 56

Medal-premium 1

A high efficiency gas furnace will not stay in operation. The unit runs for approximately 5 min then shuts down by the main furnace controller with an open pressure switch flash code. which of the following is not a proper test to perform in this situation?

Select one of the following:

  • check the inducer draft motor

  • Check the furnace filter

  • Check for a restricted flue pipe

  • both a and c

Question 34 of 56

Medal-premium 1

A service call is made on a mid efficiency gas furnace. on a call for heat, the induced draft motor will not operate. what is the proper trouble shooting procedure that should be taken.

Select one of the following:

  • Check for control voltage at "G" and "C" terminals at the circuit board.

  • check for control voltage across terminals "W" and "C" at the circuit board.

  • check the control voltage at the induced draft relay

  • Both B and C

Question 35 of 56

Medal-premium 1

A high efficiency gas furnace that uses a controller will not energize the blower motor after a pre selected 45sec time on setting. Which of the following would be the most correct trouble shooting procedure?

Select one of the following:

  • measure the resistance across the furnace controller low speed terminal and common.

  • measure the resistance across the furnace controller high speed terminal and common

  • measure the voltage to the motor and test the run capacitor

  • measure the amperage on the blower motor and test the run capacitor.

Question 36 of 56

Medal-premium 1

when servicing a mid efficiency gas furnace the thermostat has been turned to the off position but the burners remain lit and the induced draft motor continues to operate. which of the following would be the most correct troubleshooting procedure?

Select one of the following:

  • determine if the thermostat is open and check voltage at the gas valve

  • check for voltage at the indoor blower motor.

  • replace the control module

  • check the ignition system

Question 37 of 56

Medal-premium 1

on a high efficiency gas furnace that uses a controller the indoor blower motor will not de energize after its pre selected off delay setting. which of the following is a logical repair for the system.

Select one of the following:

  • replace the run capacitor

  • replace the blower motor

  • replace the control module

  • change the speed setting on the control module

Question 38 of 56

Medal-premium 1

The burners on a gas furnace cycle for approximately 3 to 4 min. during a call for heat. the system does not provide adequate heat for the home.

Technician A has determind that a new thermostat has been installed and that the heat anticipator was incorectly adjusted

Technician B cleans the position of the flame sensor and claim that this was the fault

Whos correct?

Select one of the following:

  • tech A

  • Tech B

  • both are correct

  • both are incorrect

Question 39 of 56

Medal-premium 1

A gas furnace has recently been converted to LP gas. on a call for heat the furnace is not firing correctly and is starting to soot up. what would be the most likely cause for this problem?

Select one of the following:

  • Low LPG pressure

  • too long of a burner cycle

  • wrong orifice size installed

  • all of the above

Question 40 of 56

Medal-premium 1

when inspecting a gas furnace it is noticed that the burner flames are very small in height. what action should be taken by the technician?

Select one of the following:

  • replace the gas valve

  • replace the orifices

  • check the pressure and adjust the primary air shutters if needed

  • contact the utility company to replace the gas meter

Question 41 of 56

Medal-premium 1

a customer is experiencing a loud delayed ignition from his gas furnace.

Tech A says its possible that the gas valve is not opening or closing properly

Tech B claims that its possible that after the furnace had been cleaned the burner were not properly aligned.

whos correct?

Select one of the following:

  • Tech A

  • Tech B

  • both right

  • both wrong

Question 42 of 56

Medal-premium 1

A customer called in complaining that his indoor blower would not stop running. what is the most possible cause of this problem?

Select one of the following:

  • a defective blower motor run capacitor

  • contacts stuck open on the fan control

  • contacts stuck closed on the fan control

  • both A and C

Question 43 of 56

Medal-premium 1

after diagnosing a no heat call it has been determined that the induced draft motor is not operating.

Tech A says that it is the fault of an induced draft pressure switch

Tech B states that the indoor blower relay module is defective.

Select one of the following:

  • Technician A

  • Technician B

  • both are right

  • both are wrong

Question 44 of 56

Medal-premium 1

The burners on a gas fired furnace are continously lit and setting the thermostat to the off position doesnt not make any difference. What is a possible problem for this fault ?

Select one of the following:

  • a defective gas valve

  • a defective fan control

  • a limit control stuck in the closed position

  • a shorted secondary winding on the transformer

Question 45 of 56

Medal-premium 1

a customer complains that she has no head and that the furnace does nothing at all. she says that it is a mid efficiency gas furnace with an induced draft motor and a direct spark ignition system. which of the following would be likely place to start trouble shooting

Select one of the following:

  • check the fan door switch

  • check for a blown fuse

  • check for a defective furnace switch

  • all of the above

Question 46 of 56

Medal-premium 1

on a hot surface ignition system the igniter does not glow. what would be the most likely cause of this fault.

Select one of the following:

  • a bad flame sensor

  • a bad gas valve

  • a bad closed pressure switch

  • a bad igniter

Question 47 of 56

Medal-premium 1

on a spark ignition system the spark is occurring but its pilot will not light. which one would you check?

Select one of the following:

  • terminals PV and MV/Pv for 24 volts

  • test for continuity of PV coil

  • test for the gas to the pilot line

  • all of the above

Question 48 of 56

Medal-premium 1

the thermocouple on a furnace has just been replaced but the pilot light continues to go out. what test should a tech perform?

Select one of the following:

  • ensure that the pilot flame is engulfing the tip of the thermocouple 3/8"

  • test continuity of the main valve

  • test for voltage to the main gas valve

  • check for open limit control

Question 49 of 56

Medal-premium 1

an existing thermocouple has been tested with a millitvolt meter and has registered 13 millivolts. which of the following would be the correct action to take?

Select one of the following:

  • make sure that the thermostat is calling for heat

  • replace the thermocouple

  • replace the pilot gas valve

  • there is no problem with the thermocouple and it should be left alone.

Question 50 of 56

Medal-premium 1

what is an acceptable voltage for a thermocouple?

Select one of the following:

  • 30 milliV

  • 20 milliV

  • 10 milliV

  • 5 milliV

Question 51 of 56

Medal-premium 1

an indoor blower motor will run but it cycles on a internal overload protector using a digital meter.

Tech A states the meter read zero when placing it across the motors run capacitor.

Tech B states that the meter read OL when placing it across the run capacitor.

whos right?

Select one of the following:

  • Tech A

  • Tech B

  • Both right

  • both wrong

Question 52 of 56

Medal-premium 1

a furnace has been operating during the mild winters. during the cold days the 3 year old furnace doesnt provide continuous heat to satisfy the demand. the technician does a Btu input measurement by clocking the gas meter and finds the system within specifcations. the temperature rise is also within system limits which of the following would be the most correct diagnosis.

Select one of the following:

  • the furnace was undersized in heating capacity

  • the gas pressure needs to be increased

  • the duct work needs redesigning

  • none

Question 53 of 56

Medal-premium 1

during furnace operations the thermostat is quickly satisfied. the new furnace heats the entire house very quickly then shuts off on thermostat demand. which would be the most correct statement of this situation

Select one of the following:

  • the thermostat needs replacing

  • the blower speed should be increased

  • the furnace heating capacity is oversized

  • the duct system is too large

Question 54 of 56

Medal-premium 1

Two gas furnaces were installed. Both were 150 MBtu/H (150,000 Btu/H). Both furnaces may operate at the same. when one furnace is running all operations are satisfied. When both furnaces are operating at the same time the burner flames of both furnaces decrease in size. Which procedure is correct.

Select one of the following:

  • Replace the heating thermostat

  • Increase the gas pressure regulator of the first furnace

  • replace both gas valves

  • Determine if the gas piping layout is properly sized

Question 55 of 56

Medal-premium 1

On a natural gas to LPG furnace conversation

Tech A states only one burner orifice needs to be changing

Tech B states the orifices gas valve regulator spring and pilot orifice should be changed.

Select one of the following:

  • Tech A

  • Tech B

  • both are right

  • both are wrong

Question 56 of 56

Medal-premium 1

A draft test has been performed and it is indicated that there is an improper draft for the gas furnace that is being used. Whcih of the following would be the correct procedure to preform?

Select one of the following:

  • Increases the gas pressure

  • increase the inducer draft motor speed

  • check for chimney obstructions

  • replace the heat exchanger

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HVAC Practive midterm 56

Rudy Robertson
Quiz by , created about 1 year ago

This is practice for hell day on tuesday lol

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Rudy Robertson
Created by Rudy Robertson about 1 year ago
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